The present invention relates to solenoid operated valves, and has particular application in a remotely controlled valve, wherein the valve is either closed or in a fully open position such as in an electrically operated irrigation system. In U.S. Pat. No. 3,791,619, a valve construction of the type embodied in the subject invention is disclosed for use in a lawn sprinkler system that includes a diaphragm valve assembly that is effective to absorb the kinetic energy that is present in the fluid system upon closing of the valve therein to prevent the occurrence of water hammer in the system. The valve construction as described in U.S. Pat. No. 3,791,619 includes a pilot valve that communicates with a primary fluid control chamber, which chamber has a restricted passage formed therein, that communicates with an interior chamber located behind the diaphragm. A secondary fluid control chamber communicates through a passage with the inlet side of the main valve unit and beneath the diaphragm, the secondary chamber also communicating with the primary chamber. A restrictor member is located in the primary chamber and defines a spirally extending restricted passage for restricting flow of fluid therethrough, wherein flow of fluid to and from the interior chamber is restricted to produce gradual changes in the differential pressure across the diaphragm.
Although the valve construction as disclosed in U.S. Pat. No. 3,791,619 is effective to prevent the occurrence of water hammer in the fluid system in which it is installed, the helical passage as formed by the restrictor in the control chamber is not feasible for use in valve sizes from three-fourths inch to 2 inches in the same envelope size. In order to adapt the helical passage in the interior chamber as defined by the restrictor to the larger size valve, so as to allow fluid to fill the interior chamber over the diaphragm at a reasonable valve closing rate, the control chamber would have to be provided with threads that only would allow engagement of the restrictor with the outer edge therein. This would considerably weaken the engagement of the restrictor within the control chamber and would adversely effect the operation of the valve construction.